A typical solid oxide fuel cell (SOFC) stack includes multiple fuel cells separated by interconnects (IC) which provide both electrical connection between adjacent cells in the stack and channels for delivery and removal of fuel and oxidant. When hydrocarbons are used for fuel, some of the hydrocarbons may catalytically decompose or crack on the surface of the interconnect, leaving a deposit of coke. These coke deposits can clog the channels adversely affecting the performance of the fuel cell stack.
The fuel cell stack may be reconditioned, however, by refurbishing the interconnects. A typical IC refurbishment process may include the following steps: (1) singulation (separating ICs/individual fuel cells from one another), (2) removal of electrolyte debris from the IC, (3) removal of any other remaining internal stack components (if any) from the IC and (4) removal of high temperature adhesives, seals and protective coatings.
Prior singulation method includes mechanically prying the stack apart. This process is time-consuming and prone to damaging the interconnects, by chipping, cracking, or inducing camber (curvature).
After singulation, most of the electrolyte can be scraped off, but material left around the seal region is typically very well adhered to the IC and hard to remove. The last step to achieving a clean part is typically removing the metal oxide (e.g., chromium oxide) that grows on the fuel side of the chromium alloy IC and residual oxide seal material. A grit blasting process typically used in removing these oxides is costly, time consuming, difficult to control, and can cause damage to the part by inducing camber and excessive erosion of the part.